Contamination of liquid streams with various organic and inorganic pollutants is a serious global environmental problem affecting environment quality and represents significant threat to human health and safety. Substantial heavy metal contamination of aquatic environments arises from commercial mining and metal extraction processes, surfaces modification and protection processes or communal and industrial waste sites resulting from a variety of active or defunct industrial fabrication and manufacturing activities. Similarly, significant organic water pollutants, like aliphatic, aromatic, or halogenated hydrocarbons and phenols which may also occur in combination with inorganic and metal contaminants and are frequently associated with oil exploration, extraction and refining, chemicals production, or large-scale farming and food processing.
In addition to potential for significant environmental damage, polluted liquid streams represent dilute sources of desirable raw materials like heavy metals and metal oxides. For example, the Berkeley Mine Pit in Butte, Mont. alone represents an estimated 30 billion gallons of mining influenced drainage which contains ˜180 ppm of copper along with other metals and thus could yield up to 22,000 tons of pure copper by use of a small treatment facility.
An economically relevant group of prior art methods of removal of heavy metal ions from liquid solutions is based on chemical precipitation. This process is generally burdened by complexity, high cost, clear preference for extremely large facilities and high-volume operations, and efficiency decrease with decrease in concentration of pollutants. One disadvantage concerns the resulting byproduct of precipitated sludge which becomes a concentrated yet mixed contaminant source of the toxins in the source material. The conventional process relies on the fortunate co-precipitation of a variety of metal contaminants upon the addition of precipitating agents and appropriate pH adjustment. This has traditionally been a strength of the approach but results in very limited control of the selectivity of contaminant removal. As a result, the sludge precipitated is a hazardous mixture of low-value and toxic materials which makes valuable component recovery difficult and costly. Consequently, the sludge mandates further processing and costly long term disposal as a highly toxic waste. Many similar disadvantages burden alternative heavy ion removal methods that may incorporate: filtration, ion exchange, foam generation and separation, reverse osmosis, or combinations of listed processes.
Considerable market research conducted by many strategic copper metal industry consultants indicates that high grade ore reserves are becoming exhausted. For example, practitioners may need a way to use their existing recovery equipment and processes to recover metals from their plentiful but presently economically unusable low-grade ore. Currently, they can't economically use the ore as resultant process streams containing the target metal extracted from the ore are too weak and need strengthening (concentrating) to allow practical conventional target metal extraction. Thus, the economic considerations may be closely coupled with technology limitations providing for continuous motivation to improve ail aspects of the extraction process as measured by cost (capital and operational) reduction metrics.
The extraction technologies enabled by several aspects of the current invention may be adapted to address at least some of the above considerations. Additional features of the current invention, for example, may contribute to the feasibility of modifying prior art electrowinning technology so that it can be used to economically concentrate copper generated in low-grade process streams instead of simply removing it. In general, the disclosed embodiments of the advanced electrochemical modifications technology may prepare a process stream so the customer can produce new copper from currently impractical sources with existing in-place processing infrastructure, equipment, and processes.
In particular, the present invention may provide some innovative features for unlocking this vast and vitally needed resource. Typical mines contain significant amounts of their copper in such unviable ores. This invention may allow the use of this “waste” ore and thereby increase average heap leach mine ore utilization and overall output by 25% and thus globally yield 3 Billion lbs/yr of newly recoverable copper.
Furthermore, additional features of embodiments of the current invention may allow for practical metal recovery from: Leach processing of other metals, Acid Rock Drainage (ARD), heavy metal and radionuclide contaminated sites, and metal contaminated industrial effluents such as electrowinning, plating plant, pickling operations, and circuit board manufacture (etching) discharges.